C# - SortedList Class

The SortedList class represents a collection of key-and-value pairs that are sorted by the keys and are accessible by key and by index.

A sorted list is a combination of an array and a hash table. It contains a list of items that can be accessed using a key or an index. If you access items using an index, it is an ArrayList, and if you access items using a key, it is a Hashtable. The collection of items is always sorted by the key value.

Methods and Properties of the SortedList Class

The following table lists some of the commonly used properties of the SortedList class −

Sr.No.	Property & Description
1	Capacity Gets or sets the capacity of the SortedList.
2	Count Gets the number of elements contained in the SortedList.
3	IsFixedSize Gets a value indicating whether the SortedList has a fixed size.
4	IsReadOnly Gets a value indicating whether the SortedList is read-only.
5	Item Gets and sets the value associated with a specific key in the SortedList.
6	Keys Gets the keys in the SortedList.
7	Values Gets the values in the SortedList.

The following table lists some of the commonly used methods of the SortedList class −

Sr.No.	Method & Description
1	public virtual void Add(object key, object value); Adds an element with the specified key and value into the SortedList.
2	public virtual void Clear(); Removes all elements from the SortedList.
3	public virtual bool ContainsKey(object key); Determines whether the SortedList contains a specific key.
4	public virtual bool ContainsValue(object value); Determines whether the SortedList contains a specific value.
5	public virtual object GetByIndex(int index); Gets the value at the specified index of the SortedList.
6	public virtual object GetKey(int index); Gets the key at the specified index of the SortedList.
7	public virtual IList GetKeyList(); Gets the keys in the SortedList.
8	public virtual IList GetValueList(); Gets the values in the SortedList.
9	public virtual int IndexOfKey(object key); Returns the zero-based index of the specified key in the SortedList.
10	public virtual int IndexOfValue(object value); Returns the zero-based index of the first occurrence of the specified value in the SortedList.
11	public virtual void Remove(object key); Removes the element with the specified key from the SortedList.
12	public virtual void RemoveAt(int index); Removes the element at the specified index of SortedList.
13	public virtual void TrimToSize(); Sets the capacity to the actual number of elements in the SortedList.

Example

The following example demonstrates the concept −

Live Demo

using System;
using System.Collections;

namespace CollectionsApplication {
   class Program {
      static void Main(string[] args) {
         SortedList sl = new SortedList();
         
         sl.Add("001", "Zara Ali");
         sl.Add("002", "Abida Rehman");
         sl.Add("003", "Joe Holzner");
         sl.Add("004", "Mausam Benazir Nur");
         sl.Add("005", "M. Amlan");
         sl.Add("006", "M. Arif");
         sl.Add("007", "Ritesh Saikia");
         
         if (sl.ContainsValue("Nuha Ali")) {
            Console.WriteLine("This student name is already in the list");
         } else {
            sl.Add("008", "Nuha Ali");
         }

         // get a collection of the keys. 
         ICollection key = sl.Keys;

         foreach (string k in key) {
            Console.WriteLine(k + ": " + sl[k]);
         }
      }
   }
}

When the above code is compiled and executed, it produces the following result −

001: Zara Ali
002: Abida Rehman
003: Joe Holzner
004: Mausam Banazir Nur
005: M. Amlan 
006: M. Arif
007: Ritesh Saikia
008: Nuha Ali

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